What are the causes and treatment options for a persistent cough in older adults?

Causes of Persistent Cough in Older Adults

The most common causes of persistent cough in older adults are postnasal drip syndrome, gastroesophageal reflux disease (GORD), and asthma, which together account for 85% of all cases. 1 These three conditions should be systematically evaluated and treated in older adults presenting with chronic cough.

Common Causes of Persistent Cough in Older Adults

1. Upper Airway Causes

• Postnasal drip syndrome/Upper airway cough syndrome
  • Presents with sensation of secretions in throat, frequent throat clearing
  • Often associated with rhinitis or sinusitis
  • Treatment: Trial of topical nasal corticosteroids and first-generation antihistamines with decongestants 2

2. Lower Airway Causes

• Asthma and cough-variant asthma

  • May present without typical wheezing
  • Can be triggered by cold air, exercise, or allergens
  • Diagnosis supported by bronchodilator response or positive bronchial provocation test

• COPD

  • Usually associated with phlegm production and breathlessness
  • Smoking history is typically present
  • Persistent cough in smokers may indicate risk of developing COPD 3

• Eosinophilic bronchitis

  • Normal spirometry but increased eosinophils in sputum
  • Responds to inhaled corticosteroids

• Bronchiectasis

  • Can present as "dry" bronchiectasis without typical sputum production
  • History of past respiratory insult may be present
  • Prevalence among cough clinic patients is approximately 4% 3

3. Gastroesophageal Causes

• Gastroesophageal reflux disease (GORD)
  • Often occurs without typical reflux symptoms
  • May be associated with cough during eating, after meals, or during phonation
  • Treatment: Intensive acid suppression with PPIs and alginates for minimum 3 months, plus lifestyle modifications 2

4. Medication-Related Causes

• ACE inhibitors
  • Can cause cough in up to 16% of patients
  • Not dose-related and onset time varies (hours to >1 year)
  • Cough may take up to 40 weeks to resolve after discontinuation
  • Risk factors: smoking, East Asian ethnicity, previous ACE inhibitor cough 3
  • Most patients can tolerate angiotensin II receptor blockers as alternatives 3

5. Other Important Causes

• Lung cancer

  • Cough is the fourth most common presenting feature 3
  • Red flags: hemoptysis, weight loss, recurrent pneumonia, persistent fever 2

• Pertussis infection

  • Can cause persistent cough in adults
  • In one series, 10% of chronic cough cases had positive nasal swabs for Bordetella 3

• Occupational exposures

  • Workplace sensitizers can lead to chronic cough
  • Thorough occupational history should be obtained 3

Diagnostic Approach

1. Mandatory baseline investigations:

   • Detailed history focusing on cough characteristics, triggers, and associated symptoms
   • Chest radiograph
   • Spirometry with bronchodilator response 2

2. Additional investigations when indicated:

   • Bronchial provocation testing for suspected asthma with normal spirometry
   • High-resolution CT scan when other investigations are normal
   • Esophageal pH monitoring for suspected GORD without typical symptoms 2

Treatment Algorithm

1. Address modifiable factors:

   • Stop ACE inhibitors (if applicable)
   • Smoking cessation
   • Reduce occupational exposures

2. Treat based on suspected cause:

   • For postnasal drip: nasal corticosteroids and antihistamines with decongestants
   • For asthma: inhaled corticosteroids and bronchodilators
   • For GORD: PPIs, alginates, and lifestyle modifications for at least 3 months

3. For refractory cough:

   • Consider neuromodulatory agents (gabapentin, pregabalin)
   • Low-dose morphine for severe cases
   • Speech therapy techniques 4
   • Consider referral to specialist cough clinic

Important Considerations

• Multiple causes are common in persistent cough, particularly in older adults
• Cough suppression may be contraindicated when cough clearance is important (e.g., bronchiectasis)
• Chronic cough causes substantial physical and emotional morbidity in older adults 1
• The clinical profile of chronic cough in older adults is similar to that in younger adults, with only minor differences 1

Remember that a systematic approach to diagnosis and treatment remains the most effective way to manage chronic cough in older adults, with the goal of identifying and treating the underlying cause to improve quality of life.